Snap action switch



G. M. HAUSLER 2,429,813

SNAP ACTION SWITCH Filed Aug. 15, 1946 Inventor George M. Hausler,

' His Attorney.

Patented Oct. 28, 1947 SNAP ACTION SWITCH George M. Hausler,Schenectady, N. Y., assignor to General Electrlccompany, 8- corporationof New York Application August 15, 1946, Serial No. 690,622

3 Claims. (Cl. 200-67) My invention relates to snap action electricswitches and moreparticularly to snap acting switches especially adaptedfor slow actuation as by camming means and the like. The invention hasfor its object the provision of a new and novel switch of this characterwhich is composed of a minimum number of parts and which is simple andinexpensive in construction without sacrifice of capacity, reliability,and durability.

In carrying out my invention, I utilize a switch member comprising asingle unitary strip of spring material slotted to provide a tensionmember and a pair of spaced apart compression members in' opposingrelation, the tension and compression members being connected atopposite outer ends of the strip. The juxtaposed ends of the compressionmembers each pivotally en- It is a particular object of my invention to'provide a snap action switch of the above type carrying at one end ofthe spring strip a contact which is arranged for over-center movementthrough its position of zero pressure with respect to the fixed contact.Such a switch may be referred to as a no zerof switch. By this term itis meant that the switch is arranged to maintain upon the fixed contacta positive pressure until over-center movement of the spring strip isstarted. Once the over-center movement is started, it is self-completingwithout further movement of the actuating member, so that the movablecontact passes through its position of zero pressure substantiallyinstantaneously and can, under no circumstances; be stopped in a deadcenter position of zero pressure.

For a more complete understanding of my inventionand a furtherappreciation of itsobjects and advantages, reference should now be hadto the following detailed specification'taken in conjunction with theaccompanying drawing in which Fig. 1 is a side elevation of acam-actuated snap action electric switch embodying my invention; Fig. 2is a plan view of the switch shown Referring now-to thedrawings. I haveshown my invention in one form as applied to a camactuated snap actionswitch comprising a base i preferably formed of a molded insulatingcompound, a supporting member 2 mounted in the base and a switch member3 formed of. slotted spring material and carried by the supportingmember 2. The'switch member 3 itself is a unitary fiat strip of springmaterial slotted longitudinally at 4 and 5 as best shown at Fig. 2 toprovide a pair of outer tension arms 3a and 3b and a central pair ofopposing compression arms 30 and 3d in spaced relation. 'The compressionarms 30 and'3d are slightly deformable in compression and are formed bydividing the single central arm of the strip transversely in the regionof. its center so that the inner ends of the arms 30 and 3d are injuxtaposed relation. vAt one end of the spring strip 3 is mounted amovable contact I0 and at the other end there is provided a projectingtip 3c.

The supporting member 2 comprises a substantially rigid metal stripfixedly mounted in thebase I and carrying at one end a pair of uprightmounting posts 211 and 2b, as illustrated in. the drawing. The other endof the supporting member 2 protrudes from the opposite side of the baseI to form a terminal connector I In the illustrated embodiment themounting posts 2a and 2b are formed by cuttingout and turning up twocentral portions of the supporting member 2 itself. The posts 2a and 2bare V-shaped at their upper ends to provide pivot seats for the innerorjuxtaposed ends of .pression arms 30 and 3d in the plane of the springstrip 3, so that when the spring strip is mounted upon the posts thecompression arms are de formed slightly to one side of the plane of thesprin strip and place the outer arms 3a and 3b under tension. Thus themounting posts 2a and [217 have the form of cantilever beams and areslightly resilient in the manner of such beams, so that over-centermovement of the spring strip with respect to the compression arms 30 and3d may take place without appreciable buckling of the compression armsthemselves.

For, the purpose of limiting movement of the movable contact I 0,carried at one end of the spring strip 3, I provide a pair of spacedapart fixed contacts H and I5 disposed upon opposite sides of themovable contact and serving as stop members. It will of course beappreciated that, if desired, only one of the stop members need be usedas an electric contact. As shown in the drawing, the fixed contacts 14and I5 are formed of strips of substantially rigid metal fixedly mountedin the base I and extending through the base to provide at the oppositeside thereof terminal connectors Ida and IE1: respectively.

The switch member 3 is actuated by an L- shaped spring strip l8 mountedat one end in the base I and having its upturned end I 8a looselyconnected to the tip 36 at that end of the spring strip 3 remote fromthe movable contact l0.

The lost motion connection between the spring strip 3 and the actuatingmember I8 comprises a wide slot IS in the upturned end l8a of theactuating member into which the tip 38 of the spring strip projectsloosely. The slot I9 is considerably wider than the thickness of the tip3e. The actuating member I8 is biased upwardly, as viewed in thedrawing, into engagement with the rigid supporting member 2, therebynormally.to maintain the connected end of the spring strip 3 in itsuppermost position above the pivot points of the compression members 30and 3d. In this normal position, as illustrated at Fig. l, the movablecontact 10 is also in its uppermost position and in engagement with thestationary contact I4.

The upturned end 18a of the actuating member I8 is arranged forcooperation with an operating cam 20, the cam 20 moving the actuatingmember and thus the connected end of the spring strip 3 downwardly, asviewed in the drawing, to actuate the switch.

From the foregoing understanding of the component parts of my invention,its mode of operation will be understood from the following briefdescription. It should be borne in mind that fundamentally the switchdescribed above operates to move the movable contact In substantiallyinstantaneously from a position of positive pressure on one fixedcontact to a position of positive pressure on the other fixed contact,the position of zero pressure on the fixed contacts being a transientposition.

It will be observed that as the cam 20 is rotated in a clockwisedirection from the position shown at Fig. 1 to the position shown atFig. 4, it slowly moves the actuating member l8 downwardly. Theactuating member carries with it the connected end of the spring strip3. When the cam and actuating member reach the position shown at Fig. 3,the righthand end of the spring strip 3 has been moved to such aposition that the spring strip is about to move over-center with respectto the compression arm 3d. In this position, however, the spring striphas not yet reached its over-center position with respect to thecompression arm 30, so that a positive pressure is still exerted by thearm 30 to hold the movable contact III in engagement with the upperfixed contact [4. When the right side of the spring strip 3 movesover-center with respect to the compression arm 3d, upon a very slightfurther movement of the cam from the position shown at Fig. 3, the rightend of the spring'strip moves downwardly in the slot IS without furthermovement of the cam 20 or the actuating member 18. During this movementin taking up the lost motion between the spring strip and the actuatingmember, the spring strip ismoved by its own action over-center withrespect to thecompression arm 3c at the other end of the spring strip.When this second over-center action occurs, the movable contact I0 ismoved with a snap action from its upper position shown at Figs. 1 and 3to its lower position shown at Fig. 4. The over-center movement of thecontact carrying end of the spring strip moves the plane of the tensionmembers 311 and 3b below the pivot point of the compression arm 30, sothat a positive pressure is immediately applied between the movablecontact I!) and the fixed contact IS, without further downward movementof the actuating member [8. Further movement of the started. As soon assuch over-center movement occurs, it automatically effects over-centermovement of the contact carrying end of the spring strip without furthermovement of the actuating member, so that the movable contact passessubstantially instantaneously from a position of positive pressureagainst one fixed contact to a position of positive pressure against theother fixed contact. It will be understood that a similar action occursupon reverse movement.

A snap action switch of the above typeembodying my invention may bebuilt in very small sizes and with a remarkably high interruptingcapacity for both alternating and direct current in comparison to itsphysical dimensions. The switch is also suitable for precision worksince movement of the actuating member required to effect circuit makingor circuit breaking movement of the contacts is quite small and remainssubstantially constant. For example, in a typical switching device inwhich the switch member of spring material is approximately 1%" inlength, the actuating movement is approximately 1 6" and was found to besubstantially invariable after many thousands'of operations.

While I have shown and described only a preferred embodiment of myinvention by way of i1- lustration, many modifications will occur tothose skilled in the art, and I therefore wish to have it understoodthat I intend in the appended claims to cover all such modifications asfall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A snap action electric switch comprising an integral strip of springmaterial slotted longitudinally to form a plurality of substantiallyparallel resilient arms connected together at opposite outer ends ofsaid strip, one of said arms being divided transversely intermediate itsends to provide a pair of spaced apart opposing compression membershaving their ends in juxtaposition, a fixed supporting member interposedbetween and having pivotally mounted thereon the juxtaposed ends of saidcompression members thereby to support said spring strip, a movablecontact mounted upon one end of said spring strip, a pair of stopmembers including a cooperating fixed contact positioned in spacedrelation on opposite sides of said one end of said spring strip, andlost motion actuating means connected to the other end of said springstrip for moving said other end over-center with respect to the adjacentcompression member, said over-center movement 2,42aeia moving said oneend of said spring strip over-center, thereby to move said movablecontact between said stop members with a snap action.

2. A snap action electric switch comprising an integral strip of springmaterial slotted longitudinally to form a plurality of substantiallyparallel resilient arms connected together at opposite outer ends oisaid strip, one of said arms being divided transversely intermediate itsends to provide a pair of spaced-apart opposing compression membershaving their ends in juxtaposition,

a fixed supporting member interposed between and having pivotallymounted thereon the juxtaposed ends of said compression members therebyto support said spring strip, a movable contact mounted upon one end 01'said spring strip, a pair of stop members including a cooperating fixedcontact positioned in spaced relation on opposite sides of said one endof said spring strip, a movable actuating member, and lost motion meansconnecting said actuating member to move the other end of said stripover-center with respect to the adjacent compression member, saidovercenter movement carrying said spring strip overcenter with respectto the other compression member, thereby to move said movable contactbetween said stops with a snap action.

3. A snap action electric switch comprising an integral strip of springmaterial slotted longitudinally to form a plurality of substantiallypar- 6 allel resilient arms connected together at opposite outer ends ofsaid strip, one or said arms being divided transversely intermediate itsends to provide a pair of spaced apart opposing compression membershaving their ends in juxtaposition, a fixed supporting member interposedbetween and having lvotally mounted thereon the juxtaposed ends of saidcompression members thereby to support said spring strip, saidsupporting member being wider between said juxtaposed ends than thenormal space between said ends in the plane of said spring strip, amovable contact mounted upon one end of said spring strip, a pair ofstop members including acooperating fixed contact positioned in spacedrelation on 0pposite sides of said one end of said spring strip, amovable actuating member, a lost motion connection between saidactuating member and the other end of said strip, means biasing saidactuating member to a predetermined normal position, and camming meansarranged to move said actuating member slowly in a direction to movesaid other end of said strip over-center with re spect to the adjacentcompression member, said strip upon over-center movement taking up saidlost motion and moving over-center with respect to the other of saidcompression members, thereby to move said movable contact between saidstop members with a snap action.

GEORGE M. HAUSLER.

